1. Field of the Invention
The present invention relates to a connector lock mechanism which, when a set of male and female connectors are engaged with each other, if the length of the mutual engagement of the two connectors reaches a preset length, locks the mutually connected condition of the male and female connectors and, in particular, to an improved connector lock mechanism which is capable of detecting the incomplete engagement (half engagement) between the male and female connectors.
2. Description of the Related Prior Art
Conventionally, when a plurality of electrical wires are electrically connected together or circuit boards equipped in various equipment are electrically connected to electrical wires, generally, there has been widely used a system in which such connection can be achieved by means of mutual engagement between a set of male and female connectors. That is, if a set of male and female connectors respectively formed of insulating resin or the like are engaged with each other, then male- and female-type terminals respectively stored within the female and male connectors are engaged with each other to thereby complete the mutual electrical connection between the male and female connectors. On the other hand, if the mutual engagement between the male and female connectors is removed, that is, if the two connectors are separated from each other, then the electrical connection between the male- and female-type terminals is likewise removed.
Therefore, the male and female connectors include a connector lock mechanism which is able to lock the two connectors in a well connected condition, that is, in such a manner that it can prevent inadvertent disengagement between the male and female connectors due to vibrations applied thereto under the connector operating environment.
An example of the conventional connector lock mechanisms is disclosed in Japanese Utility Model Publication No. 1-98484 of Heisei and the like. In particular, in the conventional connector lock mechanism, there are employed a set of male and female connectors 1 and 2 which are shown in FIG. 28. One connector 1 includes a pair of flexible arms 11 and 12, which respectively extend along the direction of arrow M in which one connector 1 can be engaged with the other connector, and two engaging portions 13 which are respectively formed on their associated flexible arms 11 and 12 in such a manner as to project therefrom. Also, the other connector 2 includes a pair of arm guide surfaces 21 and 22 which are capable of flexing their associated flexible arms 11 and 12 until the length of the mutual engagement between the two connectors reaches a preset length (i.e., when the two connectors are fully engaged), and two securing means 23 which, when the mutual engagement length reaches the preset length, can secure their associated engaging portions 13 to thereby prevent the two connectors from being removed from each other.
The two flexible arms 11 and 12 are disposed on the upper surface portion of one connector 1 in such a manner that they are spaced from each other in the lateral direction and are arranged parallel to each other. Also, the two engaging portions 13 respectively include projections which project outwardly in the lateral direction from the respective leading end portions of the two flexible arms 11 and 12.
Further, the two arm guide surfaces 21 and 22 of the other connector 2 are respectively formed on the two sides of the upper surface portion of the connector 2 in such a manner that their associated engaging portions 13 can be contacted therewith when the two connectors 1 and 2 are operated for their mutual engagement. The arm guide surfaces 21 and 22 are also formed as tapered surfaces which are able to flex their associated flexible arms 11 and 12 inwardly in the lateral direction as the mutual engagement between the two connectors progresses.
Moreover, the securing means 23 includes cavities which are respectively formed in front of the arm guide surfaces 21 and 22 in such a manner that their associated engaging portions 13 can be fitted into the securing means 23. If the connector mutual engagement advances, then male- and female-type terminals (not shown) respectively stored within the respective connectors start to be connected together. Upon further advancement the engaging portions 13 of one connector 1 are respectively engaged with the securing means 23 of the other connector 2. Thus, the male- and female-type terminals stored within their respective connectors are connected together electrically in a necessary and sufficient contact condition.
When the engaging portions 13 of one connector 1 are respectively engaged with the securing means 23 of the other connector 2, the inwardly flexed conditions of the respective flexible arms 11 and 12 are returned back to their original conditions. A key 24 is then inserted between the engaging portions 13 and 13 to prevent the two flexible arms 11 and 12 from being flexed again. Thus, the connectors are locked in a mutual engagement condition.
To remove such locked condition, the key 24 may be pressed down to a retreat space 25 formed below the key 24, so that it is no longer between the pair of engaging portions 13 and 13. After the locked condition of the flexible arms 11 and 12 is removed, if the two connectors 1 and 2 are pulled apart, then the connectors can be disengaged.
The pressing force necessary to bring the two connectors 1 and 2 into mutual engagement in the above-mentioned manner varies depending on the dimensional errors of the connectors 1, 2, and the dimensional errors of the male- and female-type terminals stored within their respective connectors. For example, as shown in FIG. 29, even if the engaging operation is executed with a given pressing force, there can occur an operation mistake or a wrong operation; that is, the engaging operation can be ended in a partially engaged condition in which the engaging portions 13 of the flexible arms 11 and 12 do not arrive at their associated securing means 23 but they remain in the flat portions 21a and 22a of the arm guide surfaces 21 and 22 which are located before the securing means 23.
If the connectors are used in such incomplete or partially engaged condition, for example, in a wire harness connector which is used in an automobile, there is a possibility that the mutual engagement between the two connectors 1 and 2 can be removed by vibrations applied thereto while the automobile is running and thus the electrical system of the automobile can be dysfunctional to thereby incur an accident.
In view of this, conventionally, after the engagement step is completed, there has been carried out a conduction test which checks the connectors to confirm that they are fully engaged.
However, as shown in FIG. 29, even in the partially engaged condition, when the mutual engagement length between the two connectors 1 and 2 is relatively large, there can occur a case in which the female- and male-type terminals respectively stored within their associated connectors 1 and 2 can be connected together electrically. In particular, contact resistance caused by the connection of the male- and female-type terminals can maintain the mutually connected condition between the two connectors. As a result, there is a possibility that the conduction test will provide a positive conduction test result despite the fact that the connectors are not fully engaged; that is, the partial engagement between the two connectors can be overlooked.
In view of the above, for example, in Japanese Patent Publication No. 9-180820 of Heisei and the like, there is proposed a partial engagement preventive connector lock mechanism in which, in order to be able to detect the partial engaged condition through the conduction test, there are provided within the connector housings compression springs which are used to apply repulsive forces to the male and female connectors 1 and 2 in their mutually removing directions.
With the use of this structure, if the repulsive forces (spring constants) of the compression springs are set larger than the contact resistance caused by the mutual connection between the male and female terminals, then, when the connectors are engaged together in a partial engaged condition, the two connectors 1 and 2 can be forced apart from each other by the repulsive forces of the compression springs until the mutually connected condition between the male- and female-type terminals is removed, which makes it possible to detect the partial engagement condition positively.
However, with use of the above-mentioned structure which employs the compression springs which are separate parts, not only the number of parts required in the connectors and the number of assembling steps thereof increase, which in turn increases the cost of the connector, but also a storage space for the compression springs within the connector must be provided, thereby increasing the sizes of the connectors.